Have you read the full reports, which cover thousands of pages? I would guess that you haven’t—but my apologies if you have. I’ve read about 2/3s of the 3000 pages in the most recent one, and I have read most previous IPCC reports as well. In short, I think you actually demonstrate some of my criticism: An intellectual over-confidence in one’s abilities to outsmart others, which leads to erroneous conclusions and cherry-picking. It’s similar in style to Eliezer’s claim on another thread that sexual relations between co-workers are unproblematic in a high-risk work environment, based on his assumed superior ways of reasoning—a claim which flies in the face of tried and true best practices in most high-risk work environments.
Most climate researchers are extremely worried about what we’re facing. Most people who have been following the climate situation for many years are also extremely worried. But your own reading of some parts of IPCC reports gives you confidence that we’re going to do more or less fine? Well, to each his own. (edited this section because it was too confontational in tone)
To elaborate a bit: the reason IPCC reports don’t include anything on existential risk for humanity is that this has not been part of the IPCC mandate. There have AFAIK been no calculations of the probability that climate change will lead to human extinction, or even how many milions or billions we can assume to die prematurely over the next century because of climate change. Kemp (who’s employed at a EA aligned center) came out with an excellent article together with associates this year, which goes in more detail on these questions: Climate Endgame: Exploring catastrophic climate change scenarios | PNAS
A central epistemological point of departure—which the Kemp article briefly covers—is that IPCC have been shown historically to consistently err on the cautious side. This has to do both with the nature of achieving global agreement between researchers, with the political limitations on IPCC’s work, and also on the wish to not appear alarmist. So it is reasonable to assume that things may very well get worse than IPCC projections, but it’s unlikely that it will things will turn out to be better.
Among people who have been following the debate on climate science closely, there is high awareness that the field of climate economics has come under strong criticism in recent years. The assumptions that are put into the models (such as the influential DICE model) have been claimed to be arbitrary and often unrealistic. This is well covered in the recent IPCC report, where GDP projections are treated with much caution. Nevertheless, expectations about future GDP losses in conventional climate economics have been revised continually upwards. But GDP projections about what will happen decades from now remain among the least certain of all IPCC projections.
What we are facing, and which is well described in the IPCC reports (more so in the latest one), is that there are big challenges ahead when it comes to crops and food security, fresh water supply, vector borne diseases, and mass displacement due to various factors. Any of these things may not amount to existential risk for humanity in itself. But taken together they may lead to large-scale conflict between nuclear powers, and they will most certainly lead to a massive loss of life, and that many societies will have to be abandoned. Is this “existential”? Depends on how one defines and operationalizes the word, I guess.
I’m not claiming to have outsmarted anyone. I have claimed only that I have read the IPCC’s Fifth Synthesis Report, which is 167 pages, and it doesn’t report any existential threats to humans due to climate changes. It is the report I found to be most often-cited by people claiming there are existential threats to humans due to global warming. It does not support such claims, not even once among its thousands of claims, projections, tables, graphs, and warnings.
Neither did I claim that there is no existential threat to humanity from global warming. I claimed that the IPCC’s 5th Synth report doesn’t suggest any existential threat to humanity from global warming.
Kemp is surely right that global warming “is” an existential threat, but so are asteroid strikes. He’s also surely right that we should look carefully at the most-dangerous scenarios. But, skimming Kemp’s paper recklessly, it doesn’t seem to have any quantitative data to justify the panic being spread among college students today by authorities claiming we’re facing an immediate dire threat, nor the elevation of global warming to being a threat on a par with artificial intelligence, nor the crippling of our economies to fight it, nor failing to produce enough oil that Europe can stop funding Russia’s war machine.
And as I’ve said for many years: We already have the solution to global warming: nuclear power. Nuclear power plants are clearly NOT an existential threat. If you think global warming is an existential threat, you should either lobby like hell for more nuclear power, or admit to yourself that you don’t really think global warming is an existential threat.
The IPCC’s 5th Synth Report dismisses Kemp’s proposed “Hothouse Earth” tipping point on page 74. Kemp’s claim is based on a 2018 paper, so it is the more up-to-date claim. But Halstead’s report from August 2022 is even more up-to-date, and also dismisses the Hothouse Earth tipping point.
Anyway. Back to the 5th Synth Report. It contains surprisingly little quantitative information; what it does have on risks is mostly in chapter 2. It presents this information in a misleading format, rating risks as “Very low / Medium / Very high”, but these don’t mean a low, medium, or high expected value of harm. They seem to mean a low, medium, or high probability of ANY harm of the type described, or, if they’re smart, some particular value range for a t-test of the hypothesis of net harm > 0.
The text is nearly all feeble claims like this: “Climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income, as compared to a baseline without climate change… From a poverty perspective, climate change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security and prolong existing and create new poverty traps, the latter particularly in urban areas and emerging hotspots of hunger (medium confidence). … Climate change is projected to increase displacement of people (medium evidence, high agreement).”
I call these claims feeble because they’re unquantitative. In nearly every case, no claim is made except that these harms will greater than zero. Figure SPM.9 is an exception; it shows significant predicted reductions in crop yield, with an expected value of around a 10% reduction of crop yields in 2080 AD (eyeballing the graph). Another exception is Box 3.1 on p. 79, which says, “These incomplete estimates of global annual economic losses for temperature increases of ~2.5°C above pre-industrial levels are between 0.2 and 2.0% of income (medium evidence, medium agreement).” Another exception shows predicted ocean level rise (and I misspoke; it predicts a change of a bit more than 1 foot by 2100 AD). None of the few numeric predictions of harm or shortfall that it predicts are frightening.
In short, I’m not saying I’ve evaluated the evidence and decided that climate change isn’t threatening. I’m saying that I read the 5th Synthesis Report, which I read because it was the report most-commonly cited by people claiming we face an existential risk, and found there is not one claim anywhere in it that humans face an existential risk from climate warming. I would say the most-alarming claim in the report is that crop yields are expected to be between 10% and 25% lower in 2100 than they would be without global warming. This is still less of an existential risk than population growth, which is expected to cause a slightly greater shortfall of food over that time period; and we have 80 years to plant more crops, eat fewer cows, or whatever.
You wrote, “What we are facing, and which is well described in the IPCC reports (more so in the latest one), is that there are big challenges ahead when it comes to crops and food security, fresh water supply, vector borne diseases, and mass displacement due to various factors.” But the report I read suggests only that there are big challenges ahead when it comes to crops, as I noted above. For everything else, it just says that water supply will decline, diseases will increase, and displacement will increase. It doesn’t say, nor give any evidence, that they’ll decline or increase enough for us to worry about.
The burden of proof is not on me. The burden of proof is on the IPCC to show numeric evidence that the bad things they warn us about are quantitatively significant, and on everyone who cited this IPCC report to claim that humanity is in serious danger, to show something in the report that suggests that humanity is in serious danger. I’m not saying there is no danger; I’m saying that the source that’s been cited to me as saying there is serious existential danger, doesn’t say that.
(Halstead’s report explicitly says, “my best guess estimate is that the indirect risk of existential catastrophe due to climate change is on the order of 1 in 100,000 [over all time, not just the next century], and I struggle to get the risk above 1 in 1,000.” Dinosaur-killing-asteroid strike risk is about 1 / 50M per yr, or 1/500K per century.)
the approval process of the SPM in the 2014 AR5 Synthesis report includes a line-by-line approval process involving world governments participating in the IPCC. Synthesis report Topic sections get a section-by-section discussion by world governments. That includes petro-states. The full approval process is documented in the IPCC Fact Sheet. The approval and adoption process is political. The Acceptance process used for full reports is your best choice for unfiltered science.
The AR5report you have been reading was put out 8 years ago. That is a long time in climate science. During that time, there’s been tracking of GHG production relative to stated GHG-reduction commitments. There’s also new data from actual measurements of extreme weather events, tipping point systems, and carbon sinks and sources. If you like the synthesis report or believe in its editing process, the AR6 Synthesis report is due out. Meanwhile, there’s ongoing workshops available to watch on-line, plenty of well-known papers, and other options too. Here’s a discussion of a massive signatory list attached to a declaration of climate emergency in 2022. Climate scientists are engaged in publicly sharing information about climate change, and so there’s lots of places to find valid information.
Are we on a pathway to RCP 8.5? Well, climate researchers out of Woods Hole wrote a PNAS paper about this in 2020, challenging projections from the IEA about our being on the 4.5 heating pathway. The paper indirectly contradicts Halstead’s reliance on RCP 4.5 as our expected pathway. There are letters back and forth about it available to browse on the PNAS website, basically about the contributions of changing land carbon sinks. However, climate scientists studying global warming typically underestimate dangers and negative outcomes. For example, after Bolsonaro, it’s plausible the Amazon could easily be gone by 2050 just because of corruption and mismanagement, but that’s not really mentioned in the Woods Hole analysis.
If you want to examine interesting scenarios for real purposes, for example, to advance a 30 year business agenda, or to project plans for government or civilization out to 2100, or even just 2050, maybe you’re really into supporting a particular form of energy production, or you think you’ll live to 2100, which is plausible, then consider relying on scenarios and predictive indicators of socioeconomic pathways and GHG production, rather than relying on probabilistic forecasts. You’ll want information that is within a couple years of today. For example, did you know that it rained on the summit of Greenland in 2021 for the first time in recorded history? It’s a predictive indicator of continuing increases in melting rates for Greenland this century. The rain kept up for hours. What if it lasted for days, regularly, year after year? Larger computer models used by the IPCC to predict sea level rise don’t factor in physical processes like melt pools and drainage under glaciers, though according to Jason Box, a noted climate researcher who’s spent a lot of time studying Greenland, physical processes play a big role in Greenland ice melt. There’s been rain on parts of Greenland for awhile (in my understanding, mostly toward the coasts), but now we should expect something more.
you talked about nuclear power as a potential source of energy for the future. Could it be financed and scaled to replace fossil fuel energy production in power plants by 2050, across the world? I believe not, but if you have information to the contrary, I’m interested. Right now, I believe that all renewables are a sideshow, cheap or not, until we grasp that population decline and overall energy consumption decline are the requirements of keeping our planet livable for our current population. I support oil, gas, and coal use as part of an energy conservation plan. It’s what we use now. We won’t create new infrastructure to support radically different energy production at higher levels without increasing our GHG production, so better to keep the infrastructure we have but lessen our use of it. A lot.
Sea level rise. AR6 offers revised estimates, and NASA offers its conservative summary estimates of that data. You can play with the ranges under different scenarios, I think the projections are all too low, assuming humanity does the right thing in basic respects and is lucky in many ways.
You seem genuinely interested in why somebody was calling climate change an existential risk and then offering the AR5 Synthesis report as evidence. Well, maybe that’s what the person managed to read. It’s short, nontechnical, for policymakers. And now its outdated. If you don’t find it satisfying, keep looking for more information. You’ll either decide there’s something to worry about or form a case for why the climate emergency is mostly bunk.
Thanks a lot for taking the time to answer in such detail. You are more patient than I am. Great points.
I fully agree that reduced energy use going forward is absolutely essential. That is one reason I decided to abstain from flying some years ago, in order to send a costly signal about what is needed. I am not sure I share your pessimism concerning alternative energy sources, though. Sunny parts of the world can build out lots of solar energy—with storage—fairly quickly. Non-sunny and stable parts of the world can build nuclear energy rapidly, like France and Sweden did in the 70s and 80s.
The modelling that has been done these issues have generally found that it is feasible to arrive at zero-carbon economies within two or three decades, if one combines changes in consumption and demand with rapid build-out of low-carbon energy sources. If we abolish animal agriculture and rewild large parts of the world, stop the expansion of private car use, fly less, etc—AND build nuclear and renewables like crazy, all while starting to keep fossil fuels in the ground, things can indeed change.
Here’s a very recent study, for example, which finds that a rapid transition is possible and not extremely expensive: Empirically grounded technology forecasts and the energy transition: Joule (cell.com) Such modelling is uncertain, of course, but I don’t think the present state of research validates deep pessimism about the physical possibility of doing an energy transition. The real difficulties seem political to me: Groups and actors who are heavily invested in polluting economic sectors and activities, and will often fight against change.
(I do believe that we will have to patch things up with solar radiation management in the end though, even though that will open up a new can of worms)
Not saying that any of this is going to happen or even that it’s likely, but the possibility to turn things around is there. It strikes me as odd that so many EAs seem uninterested in working on making these changes happen. For the next couple of decades, I think that contributing to making such a transition happen may be some of the most high-impact actions possible in the entire history of humanity.
OK, Oivavoi. My complaint about renewables is that they suggest an ideological stance that is too close to the stance that is the problem:
a refusal to accept limits on economic growth and energy production.
a focus on consumption patterns rather than production patterns.
a preference to reduce costs of production and tell people to “just say no” rather than reduce consumption through increasing costs of production.
a reliance on technology to boost production rather than use existing production more efficiently.
This ideology is basically one of economic growth, and is what got us into our problem in the first place.
But thank you for sharing that resource, there’s plenty there to explore. To constrain my earlier statements against renewables, I do believe in uses like:
solar water heating.
underground cold storage.
swamp coolers.
You can read more below, if you like.
renewables as a source of additional energy production, even if cheaper than fossil fuel sources, face issues with:
intermittent production
battery storage (solar, wind)
waste disposal (nuclear)
pollution risks (nuclear)
lifetime (solar, wind)
stakeholder support
nimbyism
As a quick illustration of the problem with a consumption-focused ideology, lets think about recent transportation choices in the US. In the US there have been opportunities to build fuel-efficient cars for a long time. Instead, we chose (I’m American) energy-guzzling SUV’s and big trucks. Lighter cars, lower speed limits, aerodynamic shaping, and smaller engines would have saved a lot of fuel since the 1970′s oil crisis. Carpooling, trains, recumbent bikes with traffic lights, less urbanization, fewer cars overall, energy independence, all ideas floating around back in the 1970′s. Back then we really did have time to make those changes, I think.
We could have restrained our energy production, but kept using fossil fuels without guilt and seriously reduced GHG production but just as a side effect of reducing our energy consumption overall.
Meanwhile, scientists monitoring other resource flows, like inputs to manufacturing would have been pleased to see fewer vehicles being built, fewer consumer products overall, and a slower pace of technology change, because it takes energy, mining, waste production, and environmental destruction to make products that break or are improved on too quickly.
Imagine a car from the 1980′s that gets 50mpg, seats four, and actually drives 4 people around (at 45 mph...), most of the time, but is still in use today. Who owns it? Some person who collects a ride-share credit from the state (and has for the last 35 years) to help pay for the gas. Everyone else uses bikes for short trips and trains for long ones. And they’re relatively poor in terms of material goods that they own. But they carry no debt, have a modest savings, belong to a large middle class, and are healthy and (relatively) happy. And a lot less into consumerism.
In that alternative future, fossil fuel consumption would have gone down by a lot. We wouldn’t be fracking or using shale (much). But we would still be using oil and gas, thinking worriedly about the 0.3 GAST rise we’ve seen over the last 40 years, and wondering what to do next.
But fast forward 40 years on our real timeline. Overall energy production is not a measure of sustainability. Fossil fuel production is not a measure of sustainability. GHG production is a measure but is also externalized by consumers and power producers, as much as possible (for example, a lot of US GHG’s have effects felt in other countries, that’s why some countries want reparations for our GHG production). Right now, we are talking about a future of nuclear and solar power where not only does nuclear power and renewable energy make sense, but also a bunch of restraint in other areas of consumption once we’ve solved our energy production “problem”. But that problem is really that we don’t have cheap enough energy to produce what we want with it, meaning that our consumption is unsustainable. We don’t want to conserve energy, conserve oil, or conserve resources that make our products. We could start doing that anytime. We’re not really into it.
I just don’t see Americans simultaneously accepting abundant cheap energy AND rejecting the rest of their lifestyles, come hell or high water. Which means we’ll get both. Hell and high water.
We will do everything else the same and make a bigger mess of the environment, which after this century, might not even be possible, with our cheap renewable energy and our typical pattern of overcoming resource limits and externalizing costs onto others or onto people in the future. Amazingly, there’s no talk from the public about reducing our birth rates. We still talk about the developing world as having high birth rates, places where people suffer in poverty and consume almost no resources. Given this lack of introspection and insight, I’m not expecting enlightened consumerism out of Americans, and nor should you.
We are important to ourselves, and we need to learn how to conserve. It’s simpler, and safer, to just conserve, not get all complicated with an approach like:
conserving but also making it cheaper for us if we do not conserve but decide instead to destroy the lives of some other people with our GHG emissions, resource extraction and pollution.
In reality, the US is under direct threat from climate change, regardless of our externalization efforts. Nevertheless, the externalization efforts continue.
EDIT: I’m not sure if many people use externalize the way that I do. By “externalize”, I mean indifferently shift negative consequences of actions onto other people (humans, animals, alive now or at a later time).
Thanks! That’s a lot to digest. Do you know how “government approval” of IPCC reports is implemented, e.g., does any one government have veto power over everything in the report, and is this approval granted by leaders, political appointees, or more-independent committees or organizations?
Re. “Right now, I believe that all renewables are a sideshow, cheap or not, until we grasp that population decline and overall energy consumption decline are the requirements of keeping our planet livable for our current population”—How does this belief affect your ethics? For instance, does this mean the US should decrease immigration drastically, to force poor countries to deal with their population problem? Should the US reduce grain exports? How would you approach the problem that the voluntary birth rate is higher in dysfunctional and highly-religious cultures than in stable developed secular ones? What are we to do about religions which teach that contraception is a sin?
Well, as I understand the SPM voting process, veto approval is line-by-line, so in that sense, each sentence is approved by some representative from each country. I don’t think there’s one country that can veto while others cannot,and commentary I’ve seen on the process is vague, but seems to claim it’s a simple democracy. Let me know if you learn more.
As far as exploring the details of US immigration, grain exports, and birth rate distribution, I generally favor shifting costs for the global crisis onto developed countries, where resource consumption is higher and historical responsibility for the crisis rests. Therefore, paying for the reparations that the Global South wants (some $700 billion, I read someplace) is a good idea.
Reducing birth rates in all countries is appropriate, and typical measures are such things as:
free health services.
free birth control (edit: I mean contraception).
free health education.
support of education and economic rights for women.
I think the focus of family planning belongs on developed countries where resource consumption is higher. The concern is number of births, not global immigration flows.
If I were a longtermist, I would favor a generation-on-generation use of family planning to discourage population growth, leading, within some few hundred years, to a small Earth population, that can then remain stable for many millennia. My idea of small is a few million people. That further allows human beings to stay within an ecological niche rather than destroy the resources that they need for long-term survival on planet Earth. Obviously, I am less concerned with technological stagnation than some.
EDIT: I should make clear that:
family planning has plenty of critics. I don’t have much sympathy for their views, but since family planning is a controversial topic, I expect that critics of the idea will prevent proactive family planning in some developed countries.
my view of an ethical longtermist goal is not popular among self-identified EA longtermists. I believe that they expect a larger population overall in several hundred or thousand years from now to be both feasible and desirable. I do not.
family planning is a voluntary opportunity for young couples. Family planning allows couples to choose the number of children that they will have, and in particular puts power over reproduction into the hands of women who can then choose whether to conceive.
family planning services also give individuals the means to choose self-sterilization if they desire. For example, I had a vasectomy done a long time ago, as I did not expect to ever have children.
I am not settled on a few million as a final number for a long-term population of the planet. The final number would depend on how large a population is needed to:
support what level of technology satisfactorily.
allow specialization of skills sufficient to provide high-quality services to the public such as engineering, teaching, accounting, etc.
maintain genetic diversity in the population over millennia, given that not all people will choose to have children at all.
maintain the population given the lifespan that people in the society choose.
You had mentioned concern about there being no statements of existential threat from climate change. Here’s the UN Secretary General’s speech on climate change where he claims that climate change is an existential threat.
I don’t believe the UN Secretary General shares my views on population or renewables.
Why only a few million? You’ll have to kill 9 billion people, and to what purpose? I don’t see any reason to think that the current population of humans wouldn’t be infinitely sustainable. We can supply all the energy we need with nuclear and/or solar power, and that will get us all the fresh water we need; and we already have all the arable land that we need. There just isn’t anything else we need.
Re. “You had mentioned concern about there being no statements of existential threat from climate change. Here’s the UN Secretary General’s speech on climate change where he claims that climate change is an existential threat.”
No; I said that when I traced claims of existential threat from climate change back to their source, the trail always led back to the IPCC, and the latest IPCC summary report didn’t mention anything remotely close to an existential threat to humans. This is yet another instance—the only source cited is the IPCC.
I was writing about family planning, Phil, not killing people. if you want to communicate with me, you’ll have to read what I write with more care. I was writing about family planning, and there am concerned about reducing conception, primarily, as opposed to providing, for example, abortion services. If you understand what family planning is, you’ll recognize that it is not genocide.
Have you read the full reports, which cover thousands of pages? I would guess that you haven’t—but my apologies if you have. I’ve read about 2/3s of the 3000 pages in the most recent one, and I have read most previous IPCC reports as well. In short, I think you actually demonstrate some of my criticism: An intellectual over-confidence in one’s abilities to outsmart others, which leads to erroneous conclusions and cherry-picking. It’s similar in style to Eliezer’s claim on another thread that sexual relations between co-workers are unproblematic in a high-risk work environment, based on his assumed superior ways of reasoning—a claim which flies in the face of tried and true best practices in most high-risk work environments.
Most climate researchers are extremely worried about what we’re facing. Most people who have been following the climate situation for many years are also extremely worried. But your own reading of some parts of IPCC reports gives you confidence that we’re going to do more or less fine? Well, to each his own. (edited this section because it was too confontational in tone)
To elaborate a bit: the reason IPCC reports don’t include anything on existential risk for humanity is that this has not been part of the IPCC mandate. There have AFAIK been no calculations of the probability that climate change will lead to human extinction, or even how many milions or billions we can assume to die prematurely over the next century because of climate change. Kemp (who’s employed at a EA aligned center) came out with an excellent article together with associates this year, which goes in more detail on these questions: Climate Endgame: Exploring catastrophic climate change scenarios | PNAS
A central epistemological point of departure—which the Kemp article briefly covers—is that IPCC have been shown historically to consistently err on the cautious side. This has to do both with the nature of achieving global agreement between researchers, with the political limitations on IPCC’s work, and also on the wish to not appear alarmist. So it is reasonable to assume that things may very well get worse than IPCC projections, but it’s unlikely that it will things will turn out to be better.
Among people who have been following the debate on climate science closely, there is high awareness that the field of climate economics has come under strong criticism in recent years. The assumptions that are put into the models (such as the influential DICE model) have been claimed to be arbitrary and often unrealistic. This is well covered in the recent IPCC report, where GDP projections are treated with much caution. Nevertheless, expectations about future GDP losses in conventional climate economics have been revised continually upwards. But GDP projections about what will happen decades from now remain among the least certain of all IPCC projections.
What we are facing, and which is well described in the IPCC reports (more so in the latest one), is that there are big challenges ahead when it comes to crops and food security, fresh water supply, vector borne diseases, and mass displacement due to various factors. Any of these things may not amount to existential risk for humanity in itself. But taken together they may lead to large-scale conflict between nuclear powers, and they will most certainly lead to a massive loss of life, and that many societies will have to be abandoned. Is this “existential”? Depends on how one defines and operationalizes the word, I guess.
I’m not claiming to have outsmarted anyone. I have claimed only that I have read the IPCC’s Fifth Synthesis Report, which is 167 pages, and it doesn’t report any existential threats to humans due to climate changes. It is the report I found to be most often-cited by people claiming there are existential threats to humans due to global warming. It does not support such claims, not even once among its thousands of claims, projections, tables, graphs, and warnings.
Neither did I claim that there is no existential threat to humanity from global warming. I claimed that the IPCC’s 5th Synth report doesn’t suggest any existential threat to humanity from global warming.
Kemp is surely right that global warming “is” an existential threat, but so are asteroid strikes. He’s also surely right that we should look carefully at the most-dangerous scenarios. But, skimming Kemp’s paper recklessly, it doesn’t seem to have any quantitative data to justify the panic being spread among college students today by authorities claiming we’re facing an immediate dire threat, nor the elevation of global warming to being a threat on a par with artificial intelligence, nor the crippling of our economies to fight it, nor failing to produce enough oil that Europe can stop funding Russia’s war machine.
And as I’ve said for many years: We already have the solution to global warming: nuclear power. Nuclear power plants are clearly NOT an existential threat. If you think global warming is an existential threat, you should either lobby like hell for more nuclear power, or admit to yourself that you don’t really think global warming is an existential threat.
I don’t think the IPCC is now looking more at scenarios with a less than 3C rise in temperature out of conservatism, but because they don’t see a rise above 3C before 2100 except in RCP8.5 (Figure 2.3), which is now an unrealistically high-carbon scenario; and they were sick of news agencies reporting RCP8.5 as the “business as usual” case. (It was intended to represent the worst 10% out of just those scenarios in which no one does anything to prevent climate change.)
The IPCC’s 5th Synth Report dismisses Kemp’s proposed “Hothouse Earth” tipping point on page 74. Kemp’s claim is based on a 2018 paper, so it is the more up-to-date claim. But Halstead’s report from August 2022 is even more up-to-date, and also dismisses the Hothouse Earth tipping point.
Anyway. Back to the 5th Synth Report. It contains surprisingly little quantitative information; what it does have on risks is mostly in chapter 2. It presents this information in a misleading format, rating risks as “Very low / Medium / Very high”, but these don’t mean a low, medium, or high expected value of harm. They seem to mean a low, medium, or high probability of ANY harm of the type described, or, if they’re smart, some particular value range for a t-test of the hypothesis of net harm > 0.
The text is nearly all feeble claims like this: “Climate change is expected to lead to increases in ill-health in many regions and especially in developing countries with low income, as compared to a baseline without climate change… From a poverty perspective, climate change impacts are projected to slow down economic growth, make poverty reduction more difficult, further erode food security and prolong existing and create new poverty traps, the latter particularly in urban areas and emerging hotspots of hunger (medium confidence). … Climate change is projected to increase displacement of people (medium evidence, high agreement).”
I call these claims feeble because they’re unquantitative. In nearly every case, no claim is made except that these harms will greater than zero. Figure SPM.9 is an exception; it shows significant predicted reductions in crop yield, with an expected value of around a 10% reduction of crop yields in 2080 AD (eyeballing the graph). Another exception is Box 3.1 on p. 79, which says, “These incomplete estimates of global annual economic losses for temperature increases of ~2.5°C above pre-industrial levels are between 0.2 and 2.0% of income (medium evidence, medium agreement).” Another exception shows predicted ocean level rise (and I misspoke; it predicts a change of a bit more than 1 foot by 2100 AD). None of the few numeric predictions of harm or shortfall that it predicts are frightening.
In short, I’m not saying I’ve evaluated the evidence and decided that climate change isn’t threatening. I’m saying that I read the 5th Synthesis Report, which I read because it was the report most-commonly cited by people claiming we face an existential risk, and found there is not one claim anywhere in it that humans face an existential risk from climate warming. I would say the most-alarming claim in the report is that crop yields are expected to be between 10% and 25% lower in 2100 than they would be without global warming. This is still less of an existential risk than population growth, which is expected to cause a slightly greater shortfall of food over that time period; and we have 80 years to plant more crops, eat fewer cows, or whatever.
You wrote, “What we are facing, and which is well described in the IPCC reports (more so in the latest one), is that there are big challenges ahead when it comes to crops and food security, fresh water supply, vector borne diseases, and mass displacement due to various factors.” But the report I read suggests only that there are big challenges ahead when it comes to crops, as I noted above. For everything else, it just says that water supply will decline, diseases will increase, and displacement will increase. It doesn’t say, nor give any evidence, that they’ll decline or increase enough for us to worry about.
The burden of proof is not on me. The burden of proof is on the IPCC to show numeric evidence that the bad things they warn us about are quantitatively significant, and on everyone who cited this IPCC report to claim that humanity is in serious danger, to show something in the report that suggests that humanity is in serious danger. I’m not saying there is no danger; I’m saying that the source that’s been cited to me as saying there is serious existential danger, doesn’t say that.
(Halstead’s report explicitly says, “my best guess estimate is that the indirect risk of existential catastrophe due to climate change is on the order of 1 in 100,000 [over all time, not just the next century], and I struggle to get the risk above 1 in 1,000.” Dinosaur-killing-asteroid strike risk is about 1 / 50M per yr, or 1/500K per century.)
Here’s some information:
the approval process of the SPM in the 2014 AR5 Synthesis report includes a line-by-line approval process involving world governments participating in the IPCC. Synthesis report Topic sections get a section-by-section discussion by world governments. That includes petro-states. The full approval process is documented in the IPCC Fact Sheet. The approval and adoption process is political. The Acceptance process used for full reports is your best choice for unfiltered science.
The AR5report you have been reading was put out 8 years ago. That is a long time in climate science. During that time, there’s been tracking of GHG production relative to stated GHG-reduction commitments. There’s also new data from actual measurements of extreme weather events, tipping point systems, and carbon sinks and sources. If you like the synthesis report or believe in its editing process, the AR6 Synthesis report is due out. Meanwhile, there’s ongoing workshops available to watch on-line, plenty of well-known papers, and other options too. Here’s a discussion of a massive signatory list attached to a declaration of climate emergency in 2022. Climate scientists are engaged in publicly sharing information about climate change, and so there’s lots of places to find valid information.
Are we on a pathway to RCP 8.5? Well, climate researchers out of Woods Hole wrote a PNAS paper about this in 2020, challenging projections from the IEA about our being on the 4.5 heating pathway. The paper indirectly contradicts Halstead’s reliance on RCP 4.5 as our expected pathway. There are letters back and forth about it available to browse on the PNAS website, basically about the contributions of changing land carbon sinks. However, climate scientists studying global warming typically underestimate dangers and negative outcomes. For example, after Bolsonaro, it’s plausible the Amazon could easily be gone by 2050 just because of corruption and mismanagement, but that’s not really mentioned in the Woods Hole analysis.
If you want to examine interesting scenarios for real purposes, for example, to advance a 30 year business agenda, or to project plans for government or civilization out to 2100, or even just 2050, maybe you’re really into supporting a particular form of energy production, or you think you’ll live to 2100, which is plausible, then consider relying on scenarios and predictive indicators of socioeconomic pathways and GHG production, rather than relying on probabilistic forecasts. You’ll want information that is within a couple years of today. For example, did you know that it rained on the summit of Greenland in 2021 for the first time in recorded history? It’s a predictive indicator of continuing increases in melting rates for Greenland this century. The rain kept up for hours. What if it lasted for days, regularly, year after year? Larger computer models used by the IPCC to predict sea level rise don’t factor in physical processes like melt pools and drainage under glaciers, though according to Jason Box, a noted climate researcher who’s spent a lot of time studying Greenland, physical processes play a big role in Greenland ice melt. There’s been rain on parts of Greenland for awhile (in my understanding, mostly toward the coasts), but now we should expect something more.
you talked about nuclear power as a potential source of energy for the future. Could it be financed and scaled to replace fossil fuel energy production in power plants by 2050, across the world? I believe not, but if you have information to the contrary, I’m interested. Right now, I believe that all renewables are a sideshow, cheap or not, until we grasp that population decline and overall energy consumption decline are the requirements of keeping our planet livable for our current population. I support oil, gas, and coal use as part of an energy conservation plan. It’s what we use now. We won’t create new infrastructure to support radically different energy production at higher levels without increasing our GHG production, so better to keep the infrastructure we have but lessen our use of it. A lot.
Sea level rise. AR6 offers revised estimates, and NASA offers its conservative summary estimates of that data. You can play with the ranges under different scenarios, I think the projections are all too low, assuming humanity does the right thing in basic respects and is lucky in many ways.
You seem genuinely interested in why somebody was calling climate change an existential risk and then offering the AR5 Synthesis report as evidence. Well, maybe that’s what the person managed to read. It’s short, nontechnical, for policymakers. And now its outdated. If you don’t find it satisfying, keep looking for more information. You’ll either decide there’s something to worry about or form a case for why the climate emergency is mostly bunk.
I hope you found some of this information useful.
Thanks a lot for taking the time to answer in such detail. You are more patient than I am. Great points.
I fully agree that reduced energy use going forward is absolutely essential. That is one reason I decided to abstain from flying some years ago, in order to send a costly signal about what is needed. I am not sure I share your pessimism concerning alternative energy sources, though. Sunny parts of the world can build out lots of solar energy—with storage—fairly quickly. Non-sunny and stable parts of the world can build nuclear energy rapidly, like France and Sweden did in the 70s and 80s.
The modelling that has been done these issues have generally found that it is feasible to arrive at zero-carbon economies within two or three decades, if one combines changes in consumption and demand with rapid build-out of low-carbon energy sources. If we abolish animal agriculture and rewild large parts of the world, stop the expansion of private car use, fly less, etc—AND build nuclear and renewables like crazy, all while starting to keep fossil fuels in the ground, things can indeed change.
Here’s a very recent study, for example, which finds that a rapid transition is possible and not extremely expensive: Empirically grounded technology forecasts and the energy transition: Joule (cell.com) Such modelling is uncertain, of course, but I don’t think the present state of research validates deep pessimism about the physical possibility of doing an energy transition. The real difficulties seem political to me: Groups and actors who are heavily invested in polluting economic sectors and activities, and will often fight against change.
(I do believe that we will have to patch things up with solar radiation management in the end though, even though that will open up a new can of worms)
Not saying that any of this is going to happen or even that it’s likely, but the possibility to turn things around is there. It strikes me as odd that so many EAs seem uninterested in working on making these changes happen. For the next couple of decades, I think that contributing to making such a transition happen may be some of the most high-impact actions possible in the entire history of humanity.
OK, Oivavoi. My complaint about renewables is that they suggest an ideological stance that is too close to the stance that is the problem:
a refusal to accept limits on economic growth and energy production.
a focus on consumption patterns rather than production patterns.
a preference to reduce costs of production and tell people to “just say no” rather than reduce consumption through increasing costs of production.
a reliance on technology to boost production rather than use existing production more efficiently.
This ideology is basically one of economic growth, and is what got us into our problem in the first place.
But thank you for sharing that resource, there’s plenty there to explore. To constrain my earlier statements against renewables, I do believe in uses like:
solar water heating.
underground cold storage.
swamp coolers.
You can read more below, if you like.
renewables as a source of additional energy production, even if cheaper than fossil fuel sources, face issues with:
intermittent production
battery storage (solar, wind)
waste disposal (nuclear)
pollution risks (nuclear)
lifetime (solar, wind)
stakeholder support
nimbyism
As a quick illustration of the problem with a consumption-focused ideology, lets think about recent transportation choices in the US. In the US there have been opportunities to build fuel-efficient cars for a long time. Instead, we chose (I’m American) energy-guzzling SUV’s and big trucks. Lighter cars, lower speed limits, aerodynamic shaping, and smaller engines would have saved a lot of fuel since the 1970′s oil crisis. Carpooling, trains, recumbent bikes with traffic lights, less urbanization, fewer cars overall, energy independence, all ideas floating around back in the 1970′s. Back then we really did have time to make those changes, I think.
We could have restrained our energy production, but kept using fossil fuels without guilt and seriously reduced GHG production but just as a side effect of reducing our energy consumption overall.
Meanwhile, scientists monitoring other resource flows, like inputs to manufacturing would have been pleased to see fewer vehicles being built, fewer consumer products overall, and a slower pace of technology change, because it takes energy, mining, waste production, and environmental destruction to make products that break or are improved on too quickly.
Imagine a car from the 1980′s that gets 50mpg, seats four, and actually drives 4 people around (at 45 mph...), most of the time, but is still in use today. Who owns it? Some person who collects a ride-share credit from the state (and has for the last 35 years) to help pay for the gas. Everyone else uses bikes for short trips and trains for long ones. And they’re relatively poor in terms of material goods that they own. But they carry no debt, have a modest savings, belong to a large middle class, and are healthy and (relatively) happy. And a lot less into consumerism.
In that alternative future, fossil fuel consumption would have gone down by a lot. We wouldn’t be fracking or using shale (much). But we would still be using oil and gas, thinking worriedly about the 0.3 GAST rise we’ve seen over the last 40 years, and wondering what to do next.
But fast forward 40 years on our real timeline. Overall energy production is not a measure of sustainability. Fossil fuel production is not a measure of sustainability. GHG production is a measure but is also externalized by consumers and power producers, as much as possible (for example, a lot of US GHG’s have effects felt in other countries, that’s why some countries want reparations for our GHG production). Right now, we are talking about a future of nuclear and solar power where not only does nuclear power and renewable energy make sense, but also a bunch of restraint in other areas of consumption once we’ve solved our energy production “problem”. But that problem is really that we don’t have cheap enough energy to produce what we want with it, meaning that our consumption is unsustainable. We don’t want to conserve energy, conserve oil, or conserve resources that make our products. We could start doing that anytime. We’re not really into it.
I just don’t see Americans simultaneously accepting abundant cheap energy AND rejecting the rest of their lifestyles, come hell or high water. Which means we’ll get both. Hell and high water.
We will do everything else the same and make a bigger mess of the environment, which after this century, might not even be possible, with our cheap renewable energy and our typical pattern of overcoming resource limits and externalizing costs onto others or onto people in the future. Amazingly, there’s no talk from the public about reducing our birth rates. We still talk about the developing world as having high birth rates, places where people suffer in poverty and consume almost no resources. Given this lack of introspection and insight, I’m not expecting enlightened consumerism out of Americans, and nor should you.
We are important to ourselves, and we need to learn how to conserve. It’s simpler, and safer, to just conserve, not get all complicated with an approach like:
conserving but also making it cheaper for us if we do not conserve but decide instead to destroy the lives of some other people with our GHG emissions, resource extraction and pollution.
In reality, the US is under direct threat from climate change, regardless of our externalization efforts. Nevertheless, the externalization efforts continue.
EDIT: I’m not sure if many people use externalize the way that I do. By “externalize”, I mean indifferently shift negative consequences of actions onto other people (humans, animals, alive now or at a later time).
Thanks! That’s a lot to digest. Do you know how “government approval” of IPCC reports is implemented, e.g., does any one government have veto power over everything in the report, and is this approval granted by leaders, political appointees, or more-independent committees or organizations?
Re. “Right now, I believe that all renewables are a sideshow, cheap or not, until we grasp that population decline and overall energy consumption decline are the requirements of keeping our planet livable for our current population”—How does this belief affect your ethics? For instance, does this mean the US should decrease immigration drastically, to force poor countries to deal with their population problem? Should the US reduce grain exports? How would you approach the problem that the voluntary birth rate is higher in dysfunctional and highly-religious cultures than in stable developed secular ones? What are we to do about religions which teach that contraception is a sin?
Well, as I understand the SPM voting process, veto approval is line-by-line, so in that sense, each sentence is approved by some representative from each country. I don’t think there’s one country that can veto while others cannot,and commentary I’ve seen on the process is vague, but seems to claim it’s a simple democracy. Let me know if you learn more.
As far as exploring the details of US immigration, grain exports, and birth rate distribution, I generally favor shifting costs for the global crisis onto developed countries, where resource consumption is higher and historical responsibility for the crisis rests. Therefore, paying for the reparations that the Global South wants (some $700 billion, I read someplace) is a good idea.
Reducing birth rates in all countries is appropriate, and typical measures are such things as:
free health services.
free birth control (edit: I mean contraception).
free health education.
support of education and economic rights for women.
I think the focus of family planning belongs on developed countries where resource consumption is higher. The concern is number of births, not global immigration flows.
If I were a longtermist, I would favor a generation-on-generation use of family planning to discourage population growth, leading, within some few hundred years, to a small Earth population, that can then remain stable for many millennia. My idea of small is a few million people. That further allows human beings to stay within an ecological niche rather than destroy the resources that they need for long-term survival on planet Earth. Obviously, I am less concerned with technological stagnation than some. EDIT: I should make clear that:
family planning has plenty of critics. I don’t have much sympathy for their views, but since family planning is a controversial topic, I expect that critics of the idea will prevent proactive family planning in some developed countries.
my view of an ethical longtermist goal is not popular among self-identified EA longtermists. I believe that they expect a larger population overall in several hundred or thousand years from now to be both feasible and desirable. I do not.
family planning is a voluntary opportunity for young couples. Family planning allows couples to choose the number of children that they will have, and in particular puts power over reproduction into the hands of women who can then choose whether to conceive.
family planning services also give individuals the means to choose self-sterilization if they desire. For example, I had a vasectomy done a long time ago, as I did not expect to ever have children.
I am not settled on a few million as a final number for a long-term population of the planet. The final number would depend on how large a population is needed to:
support what level of technology satisfactorily.
allow specialization of skills sufficient to provide high-quality services to the public such as engineering, teaching, accounting, etc.
maintain genetic diversity in the population over millennia, given that not all people will choose to have children at all.
maintain the population given the lifespan that people in the society choose.
You had mentioned concern about there being no statements of existential threat from climate change. Here’s the UN Secretary General’s speech on climate change where he claims that climate change is an existential threat.
I don’t believe the UN Secretary General shares my views on population or renewables.
Why only a few million? You’ll have to kill 9 billion people, and to what purpose? I don’t see any reason to think that the current population of humans wouldn’t be infinitely sustainable. We can supply all the energy we need with nuclear and/or solar power, and that will get us all the fresh water we need; and we already have all the arable land that we need. There just isn’t anything else we need.
Re. “You had mentioned concern about there being no statements of existential threat from climate change. Here’s the UN Secretary General’s speech on climate change where he claims that climate change is an existential threat.”
No; I said that when I traced claims of existential threat from climate change back to their source, the trail always led back to the IPCC, and the latest IPCC summary report didn’t mention anything remotely close to an existential threat to humans. This is yet another instance—the only source cited is the IPCC.
I was writing about family planning, Phil, not killing people. if you want to communicate with me, you’ll have to read what I write with more care. I was writing about family planning, and there am concerned about reducing conception, primarily, as opposed to providing, for example, abortion services. If you understand what family planning is, you’ll recognize that it is not genocide.